Mathematical Models for Under-Deposit Corrosion in Aerated Media

A three-dimensional mathematical model was developed to investigate conditions under which the onset of under-deposit corrosion occurs. A model for corrosion in fluids containing dissolved oxygen is presented. The location of anodic and cathodic regions was not assumed a priori, but was rather the result of the numerical simulation, which revealed galvanic coupling caused by the formation of differential aeration cells. The model accounts for electrochemical reactions, homogeneous reactions, and deposition of reaction products which influenced the rate of the electrochemical reactions and resulted in an active-passive transition.